We have demonstrated and partially characterized phospholipase A1, A2 and lysophospholipase activities of rat gastric mucosa. The phospholipase activities are enhanced by bile salts. We plan to investigate the mechanism whereby bile salts enhance the hydrolysis of phospholipids by phospholipase A1 and A2. In vitro investigations have shown that aspirin and salicylic acid inhibit lysophospholipase and under certain conditions enhance phospholipase A2 activity. We plan to investigate the effect of these compounds on lysolecithin metabolism in tissue secretions and in the living animal.